REPRODUCTIVE EFFORT: ITS DEFINITION, MEASUREMENT AND INTERPRETATION IN RELATION TO MOLLUSCAN LIFE-HISTORY STRATEGIES

1983 ◽  
Keyword(s):  
Life History ◽  
Reproductive Effort ◽  
Life History Strategies

scholarly journals Using life history trade-offs to understand core-transient structuring of a small mammal community

2014 ◽  
Author(s):  
Sarah R Supp ◽  
David N. Koons ◽  
S. K. Morgan Ernest
Keyword(s):  
Life History ◽  
Reproductive Effort ◽  
Survival Strategies ◽  
Life History Strategies ◽  
High Survival ◽  
Transient Species ◽  
Ecological Specialization ◽  
Core Species ◽  
Trade Offs ◽  
Source Sink

An emerging conceptual framework suggests that communities are comprised of two main groups of species: core species that are temporally persistent, and transient species that are temporally intermittent. Core and transient species have been shown to differ in spatiotemporal turnover, diversity patterns, and importantly, survival strategies targeted at local vs. regional habitat use. While the core-transient framework has typically been a site-specific designation for species, we suggest that if core and transient species have local vs. regional survival strategies across sites, and consistently differ in population-level spatial structure and gene flow, they may also exhibit different life-history strategies. Specifically, core species should display relatively low dispersal rates, low reproductive effort, high ecological specialization and high survival rates compared to transient species, which may display a wider range of traits given that transience may result from source-sink dynamics or from the ability to emigrate readily. We present results from 21 years of capture-mark-recapture data in a diverse rodent community, evaluating the linkages between temporal persistence, local abundance, and trade-offs among life-history traits. Core species at our site conservatively supported our hypotheses, differing in ecological specialization, survival and dispersal probabilities, and reproductive effort from transient species. Transient species exhibited a wider range of characteristics, which likely stems from the multiple processes generating source-sink dynamics and nomadic transience in local communities. We suggest that trait associations among core-transient species may be similar in other systems and warrants further study.

scholarly journals Between semelparity and iteroparity: empirical evidence for a continuum of modes of parity

2017 ◽  
Author(s):  
P. William Hughes
Keyword(s):  
Life History ◽  
Mathematical Models ◽  
Molecular Basis ◽  
Life Histories ◽  
Life History Theory ◽  
Reproductive Effort ◽  
Theoretical Biology ◽  
Relative Fitness ◽  
Life History Strategies ◽  
Molecular Evidence

ABSTRACTThe number of times an organism reproduces (i.e. its mode of parity) is a fundamental life-history character, and evolutionary and ecological models that compare the relative fitness of strategies are common in life history theory and theoretical biology. Despite the success of mathematical models designed to compare intrinsic rates of increase between annual-semelparous and perennial-iteroparous reproductive schedules, there is widespread evidence that variation in reproductive allocation among semelparous and iteroparous organisms alike is continuous. This paper reviews the ecological and molecular evidence for the continuity and plasticity of modes of parity––that is, the idea that annual-semelparous and perennial-iteroparous life histories are better understood as endpoints along a continuum of possible strategies. I conclude that parity should be understood as a continuum of different modes of parity, which differ by the degree to which they disperse or concentrate reproductive effort in time. I further argue that there are three main implications of this conclusion: (1) That seasonality should not be conflated with parity; (2) that mathematical models purporting to explain the evolution of semelparous life histories from iteroparous ones (or vice versa) should not assume that organisms can only display either an annual-semelparous life history or a perennial-iteroparous one; and (3) that evolutionary ecologists should examine the physiological or molecular basis of traits underlying different modes of parity, in order to obtain a general understanding of how different life history strategies can evolve from one another.

scholarly journals Sex-specific predation risk and the evolution of sexual dimorphism in immunocompetence: a theoretical analysis

2014 ◽  
Author(s):  
Benjamin Fanson ◽  
Eirik Søvik
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Sexual Dimorphism ◽  
Immune Function ◽  
Predation Risk ◽  
Reproductive Effort ◽  
Life History Strategies ◽  
Defense Strategies ◽  
Differential Predation ◽  
Predation Costs

Sexual dimorphism in immunocompetence, with males having lower immune function, is a prevalent pattern in nature. The main evolutionary explanation for this pattern is that males preferentially allocate resources away from immune function and towards reproductive effort to increase their competitiveness for limited females. However, the role of differential predation risk between the sexes has not been considered, despite predation risk being a major driver of life history strategies and male sexual traits often having associated predation costs. It is unclear whether increased predation risk should increase or decrease investment in immune function, as males have been shown to utilize both behavioural (e.g. decrease foraging activity) and/or life-history (e.g. decrease investment in sexual trait) defense strategies to manage predation risk. Here, we modelled optimal resource acquisition and allocation towards immune function under differential predation risk with multiple defense strategies. If males have limited defense strategies, increasing predation risk caused males to trade-off immune function for reproductive effort, leading to reduced immunocompetence. In contrast, if males can only decrease predation risk through reduction of reproductive effort (e.g. decrease colouration or calling rates), then increasing predation risk causes immune function to increase. If males can utilize multiple defense strategies and sexual selection is low, then males maintain a constant immune function as predation risk increases. Sexual selection robustly resulted in decreased immunocompetence. Overall, our results suggest that predation plays an important role in the evolution of sexual dimorphism in immunocompetence, but predicting its effect requires understanding the integrated defense strategies available.

scholarly journals Sex-specific predation risk and the evolution of sexual dimorphism in immunocompetence: a theoretical analysis

2014 ◽  
Author(s):  
Benjamin Fanson ◽  
Eirik Søvik
Keyword(s):  
Sexual Selection ◽  
Life History ◽  
Sexual Dimorphism ◽  
Immune Function ◽  
Predation Risk ◽  
Reproductive Effort ◽  
Life History Strategies ◽  
Defense Strategies ◽  
Differential Predation ◽  
Predation Costs

Sexual dimorphism in immunocompetence, with males having lower immune function, is a prevalent pattern in nature. The main evolutionary explanation for this pattern is that males preferentially allocate resources away from immune function and towards reproductive effort to increase their competitiveness for limited females. However, the role of differential predation risk between the sexes has not been considered, despite predation risk being a major driver of life history strategies and male sexual traits often having associated predation costs. It is unclear whether increased predation risk should increase or decrease investment in immune function, as males have been shown to utilize both behavioural (e.g. decrease foraging activity) and/or life-history (e.g. decrease investment in sexual trait) defense strategies to manage predation risk. Here, we modelled optimal resource acquisition and allocation towards immune function under differential predation risk with multiple defense strategies. If males have limited defense strategies, increasing predation risk caused males to trade-off immune function for reproductive effort, leading to reduced immunocompetence. In contrast, if males can only decrease predation risk through reduction of reproductive effort (e.g. decrease colouration or calling rates), then increasing predation risk causes immune function to increase. If males can utilize multiple defense strategies and sexual selection is low, then males maintain a constant immune function as predation risk increases. Sexual selection robustly resulted in decreased immunocompetence. Overall, our results suggest that predation plays an important role in the evolution of sexual dimorphism in immunocompetence, but predicting its effect requires understanding the integrated defense strategies available.

scholarly journals Using life history trade-offs to understand core-transient structuring of a small mammal community

2015 ◽  
Author(s):  
Sarah R Supp ◽  
David N. Koons ◽  
S. K. Morgan Ernest
Keyword(s):  
Life History ◽  
Reproductive Effort ◽  
Survival Strategies ◽  
Life History Strategies ◽  
High Survival ◽  
Transient Species ◽  
Ecological Specialization ◽  
Core Species ◽  
Trade Offs ◽  
Source Sink

An emerging conceptual framework suggests that communities are composed of two main groups of species through time: core species that are temporally persistent, and transient species that are temporally intermittent. Core and transient species have been shown to differ in spatiotemporal turnover, diversity patterns, and importantly, survival strategies targeted at local vs. regional habitat use. While the core-transient framework has typically been a site-specific designation for species, we suggest that if core and transient species have local vs. regional survival strategies across sites, and consistently differ in population-level spatial structure and gene flow, they may also exhibit different life-history strategies. Specifically, core species should display relatively low movement rates, low reproductive effort, high ecological specialization and high survival rates compared to transient species, which may display a wider range of traits given that transience may result from source-sink dynamics or from the ability to emigrate readily in a nomadic fashion. We present results from 21 years of capture-mark-recapture data in a diverse rodent community, evaluating the linkages between temporal persistence, local abundance, and trade-offs among life-history traits. Core species at our site conservatively supported our hypotheses, differing in ecological specialization, survival and movement probabilities, and reproductive effort relative to transient species. Transient species exhibited a wider range of characteristics, which likely stems from the multiple processes generating transience in local communities, such as source-sink dynamics at larger regional scales or nomadic life history strategies. We suggest that trait associations among core-transient species may be similar in other systems and warrants further study.

scholarly journals Macroevolution of dimensionless life history metrics in tetrapods

2019 ◽  
Author(s):  
Cecina Babich Morrow ◽  
S. K. Morgan Ernest ◽  
Andrew J. Kerkhoff
Keyword(s):  
Life History ◽  
Body Mass ◽  
Life History Traits ◽  
Reproductive Effort ◽  
Life History Strategies ◽  
Offspring Size ◽  
Evolutionary Transitions ◽  
Trade Offs ◽  
Survival And Reproduction ◽  
The Impact

AbstractLife history traits represent organism’s strategies to navigate the fitness trade-offs between survival and reproduction. Eric Charnov developed three dimensionless metrics to quantify fundamental life history trade-offs. Lifetime reproductive effort (LRE), relative reproductive lifespan (RRL), and relative offspring size (ROS), together with body mass, can be used classify life history strategies across the four major classes of tetrapods: amphibians, reptiles, mammals, and birds. First, we investigate how the metrics have evolved in concert with body mass. In most cases, we find evidence for correlated evolution between body mass and the three metrics. Finally, we compare life history strategies across the four classes of tetrapods and find that LRE, RRL, and ROS delineate a space in which the major tetrapod clades occupy mostly unique subspaces. These distinct combinations of life history strategies provide us with a framework to understand the impact of major evolutionary transitions in energetics, physiology, and ecology.

scholarly journals Macroevolution of dimensionless life-history metrics in tetrapods

2021 ◽  
Vol 288 (1949) ◽  
Author(s):  
Cecina Babich Morrow ◽  
S. K. Morgan Ernest ◽  
Andrew J. Kerkhoff
Keyword(s):  
Life History ◽  
Body Mass ◽  
Life History Traits ◽  
Reproductive Effort ◽  
Life History Strategies ◽  
Offspring Size ◽  
Evolutionary Transitions ◽  
Trade Offs ◽  
Survival And Reproduction ◽  
The Impact

Life-history traits represent organisms' strategies to navigate the fitness trade-offs between survival and reproduction. Eric Charnov developed three dimensionless metrics to quantify fundamental life-history trade-offs. Lifetime reproductive effort (LRE), relative reproductive lifespan (RRL) and relative offspring size (ROS), together with body mass can be used to classify life-history strategies across the four major classes of tetrapods: amphibians, reptiles, mammals and birds. First, we investigate how the metrics have evolved in concert with body mass within tetrapod lineages. In most cases, we find evidence for correlated evolution among body mass and the three dimensionless metrics. Second, we compare life-history strategies across the four classes of tetrapods and find that LRE, RRL and ROS delineate a space in which the major tetrapod classes occupy mostly unique subspaces. These distinct combinations of life-history strategies provide us with a framework to understand the impact of major evolutionary transitions in energetics, physiology and ecology.

scholarly journals Using life history trade-offs to understand core-transient structuring of a small mammal community

2015 ◽  
Author(s):  
Sarah R Supp ◽  
David N. Koons ◽  
S. K. Morgan Ernest
Keyword(s):  
Life History ◽  
Reproductive Effort ◽  
Survival Strategies ◽  
Life History Strategies ◽  
High Survival ◽  
Transient Species ◽  
Ecological Specialization ◽  
Core Species ◽  
Trade Offs ◽  
Source Sink

An emerging conceptual framework suggests that communities are composed of two main groups of species through time: core species that are temporally persistent, and transient species that are temporally intermittent. Core and transient species have been shown to differ in spatiotemporal turnover, diversity patterns, and importantly, survival strategies targeted at local vs. regional habitat use. While the core-transient framework has typically been a site-specific designation for species, we suggest that if core and transient species have local vs. regional survival strategies across sites, and consistently differ in population-level spatial structure and gene flow, they may also exhibit different life-history strategies. Specifically, core species should display relatively low movement rates, low reproductive effort, high ecological specialization and high survival rates compared to transient species, which may display a wider range of traits given that transience may result from source-sink dynamics or from the ability to emigrate readily in a nomadic fashion. We present results from 21 years of capture-mark-recapture data in a diverse rodent community, evaluating the linkages between temporal persistence, local abundance, and trade-offs among life-history traits. Core species at our site conservatively supported our hypotheses, differing in ecological specialization, survival and movement probabilities, and reproductive effort relative to transient species. Transient species exhibited a wider range of characteristics, which likely stems from the multiple processes generating transience in local communities, such as source-sink dynamics at larger regional scales or nomadic life history strategies. We suggest that trait associations among core-transient species may be similar in other systems and warrants further study.

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